Methods for treating sheet metal, which in sections have locally modified properties, are generally known. Sheet metal parts with locally modified properties can be produced by locally alloying in corresponding alloying elements. DE 196 50 258 A1 describes a method for alloying metal sheets, in which alloying components are supplied in the form of a wire and the contact area between the wire and the metal sheet is heated by means of a laser. Even if the metal sheet and the wire are fused in the contact area in order to quickly form the alloy in the contact area, this method is time-consuming because the wire and the laser beam must be successively moved to and process each contact area to be alloyed. The greater the proportion of the area to be alloyed in the overall surface of the metal sheet, the longer it takes to process a metal sheet with the known method and the more uneconomical this method becomes.